软硬不均地层及不同开挖顺序下双顶管隧道施工对管片及地层的影响
刘明友1韦宏业2么晓辉1马少坤2尉强1刘草平1邵羽3
Impact of Double Jacking Tunnel Construction on Pipe Segments and Strata under Uneven Soft\|Hard Soil Conditions and Different Excavation Sequences
LIU MingyouWEI HongyeME XiaohuiMa ShaokunWEI QiangLIU CaopingSHAO Yu
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作者信息:1.中铁上海工程局集团第五工程有限公司，530100，南宁
2.广西大学土木建筑工程学院，530004，南宁
3.广西交通设计集团有限公司，530029，南宁
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Affiliation:The Fifth Engineering of Shanghai Civil Engineering Group Co., Ltd., 530100, Nanning, China
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关键词:
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Key words:
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DOI:10.16037/j.1007-869x.2023.11.025
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中图分类号/CLCN:U455.4
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栏目/Col:研究报告
摘要:
目的：双顶管隧道穿越软硬不均地层时往往会导致周围地层变形、管片受损等一系列问题。为防止这些问题发生，应深入开展双顶管施工时地层的软硬程度、不同施工顺序对周围地层及管片的影响。方法：以南宁市平花河排水干渠顶管工程为背景，采用数值模拟方法，建立了三维有限元隧道开挖模型，分别研究了左右线同步开挖、先左线后右线两种开挖顺序下隧道横截面中黏土面积占比r1不同取值的5种工况，并对双顶管穿越不同软硬组合地层对周围土体变形及管片应力进行了分析。结果及结论：双顶管隧道穿越不同软硬组合地层所致地面沉降差异显著，地面沉降随r1的增大而增大，同步开挖工况下全断面黏土层的地面沉降最大值约为全断面石灰岩的2.2倍；双隧道先后开挖所致地面沉降值约为左右线同步开挖时的1.1倍；当隧道顶管机在监测断面往前开挖2倍隧道直径距离后，监测断面的地表沉降基本上不再发生变化；管片最大Mises应力随r1的增大而增大。
Abstracts:
Objective: Double\|top tube tunnels crossing uneven soft and hard strata often lead to a series of problems such as deformation of surrounding strata and damage to pipe segments. In order to prevent these problems from occurring frequently, it is necessary to carry out in\|depth investigation into the softness and hardness of strata as well as the effect of different construction sequences on the surrounding strata and pipe segments. Method: Based on the drainage channel pipe jacking project of Pinghua River in Nanning City, a three\|dimensional finite element tunnel excavation model is established using numerical simulation methods. Five different working conditions are selected based on the proportion of clay area r1 in the tunnel cross\|section under two excavation sequences: synchronous excavation of the left and right lines, and excavation of the left line first and then the right line.The deformation of the surrounding soil and the stress of the pipe segments during the double culvert crossing through different soft and hard soil combinations are analyzed. Result & Conclusion: The ground settlement caused by the double jacking pipe crossing various soft\|hard strata is significantly different, which increases with the increase of r1, and the maximum of the entire cross\|section clay layer under synchronous excavation is about 2.2 times that of the entire cross\|section limestone. The ground settlement caused by the excavation of the double jacking pipe in sequence is about 1.1 times that of the synchronous excavation of the left and right lines. When the tunnel jacking machine excavates forward 2 times the diameter distance of the tunnel at the monitoring section, the ground surface settlement does not change significantly. The maximum Mises stress of the pipe increases with the increase of r1.
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